269532 Microfluidic Production of Food Emulsions Containing Anisotropic-Shaped Fat Particles
Shape of particles such as ice crystals and fat particles contribute significantly to the rheology of food suspensions. For example, at the same volume fraction, a suspension of ellipsoids can generate larger shear viscosity that a suspension of spherical particles. Thus, designing particles of anisotropic shape and using them as food additives offers a promising route to control the rheology of food suspensions. However, methods to produce anisotropic food particles are scarce. Here, we report the development of microfluidic techniques to generate ellipsoidal fat particles.
We assemble cross-flow microfluidic devices, using commercially available parts and fittings. We use palm oil (Sans Trans 35) as the dispersed phase and 2% Tween 20 as the continuous phase. We preheat both the continuous and dispersed phases and inject them using syringe pumps into the cross-flow device. Oil droplets produced at the cross-junction are carried downstream. We control the temperature of the downstream section to induce crystallization in the flowing droplets. Droplet generation is viewed using optical microscopy and image analysis is conducted to quantify droplet sizes.
We find that confinement of the droplets in the microchannel together with partial-solidification of the droplets enables optimal production of ellipsoidal fat particles. The control parameters including local temperature, residence time, and flow rates of the incoming fluids sensitively affected the ability to continuously produce fat particles. The drop speed required for the production of ellipsoidal particles was lower than that for spherical fat particles. In addition, higher aspect ratio fat particles were obtained at lower flow rates of the carrier fluid.